Control of Flat Band Voltage by Partial Incorporation of La2O3 or Sc2O3 into HfO2 in Metal/HfO2/SiO2/Si MOS Capacitors

High-k/SiO2 interfacial properties are most critical factors determining the high-k gate MOSFET characteristics. We fabricated MOS capacitors of metal/HfO2/SiO2/Si structures in which were contained in the HfO2 layer. Flat-band voltage (VFB) shifts were measured by changing composition in metal/HfO2/(HfO2)1-x(La2O3)x/SiO2/Si and metal/HfO2/(HfO2)1-x(Sc2O3)x/SiO2/Si structures. It was found that VFB shift arises mainly from high-k/SiO2 interface rather than metal/high-k interface. VFB could be effectively controlled by incorporating La2O3 or Sc2O3 near the high-k/SiO2 interface.